Under certain circumstances, a flight crew or pilots of an aircraft may become incapacitated and unable to control the aircraft. One example of the flight crew becoming incapacitated may be decompression of the cockpit or cabin of the aircraft above an altitude where oxygen is needed by the crew or for some other reason there is a lack of oxygen in the cockpit or cabin. Hypoxia or lack of oxygen will cause the judgment of the crew to be impaired and eventually the crew will loose consciousness. Under such circumstances, an ability to descend the aircraft to an altitude where sufficient oxygen is present to sustain human life and to permit possible revival of the crew is needed along with the aircraft being able to be flown safely while the crew is incapacitated.
Another example where the flight crew may become incapacitated is an unauthorized pilot taking over control of the aircraft or some other impairment of the authorized flight crew. Under this scenario, the aircraft may be flown in an unsafe erratic manner or flown to a destination other than that programmed or in the flight plan. Under such circumstances, an ability to regain control of the aircraft and direct it to a safe area where minimal if any damage to other aircraft or objects on the ground is desirable.